Role of HIF-1α in reduction of apoptosis in cortical neurons of rats by sevoflurane preconditioning: the relationship with Bid, Bim and Puma

Abstract

Objective To evaluate the role of hypoxia inducible factor-1α(HIF-1α)in reduction of apoptosis in cortical neurons of rats by sevoflurane preconditioning. Methods Primary cortical neurons obtained from neonatal Sprague-Dawley rats were seeded in 6-well plates(2 ml/well), and randomly divided into 4 groups(n=15 each)using a random number table: control group(C group), anoxia-reoxygenation(A/R)group, sevoflurane preconditioning group(SP group)and HIF-1α inhibitor 2-methoxyestradiol group(H group). The neurons were subjected to O2-glucose deprivation for 90 min followed by restoration of O2-glucose supply for 24 h. In group SP, the neurons were exposed to 2.0% sevoflurane for 2 h followed by 5 min washout for 3 times, and then sevoflurane preconditioning was performed immediately.In group H, sevoflurane preconditioning was performed at 72 h of incubation with 5 μmol/L 2-methoxyestradiol.The apoptosis in neurons was assessed using Annexin Ⅴ-FITC/PI assay, and apoptosis rate was calculated.The expression of Bid, Bim, Puma and activated caspase-3 in neurons was detected by Western blot. Results Compared with group C, apoptosis rate was significantly increased, and the expression of Bid, Bim, Puma and activated caspase-3 was up-regulated in group A/R.Compared with group A/R, apoptosis rate was significantly decreased, and the expression of Bid, Bim, Puma and activated caspase-3 was down-regulated in group SP.Compared with group SP, apoptosis rate was significantly increased, and the expression of Bid, Bim, Puma and activated caspase-3 was up-regulated in group H. Conclusion HIF-1α mediates reduction of apoptosis in rat neurons by sevoflurane preconditioning, and down-regulated expression of Bid, Bim, and Puma is involved in the mechanism. Key words: Hypoxia-inducible factor 1, alpha subunit; Apoptosis regulatory proteins; Anesthetics, inhalation; Ischemic preconditioning; Cell hypoxia; Oxygen; Neurons; Apoptosis